Synthetic Study of Dragmacidin E: Construction of the Core Structure Using Pd-Catalyzed Cascade Cyclization and Rh-Catalyzed Aminoacetoxylation

We
developed a novel synthetic method of the core structure of
dragmacidin E bearing a 7-membered ring-fused bis­(indolyl)­pyrazinone
skeleton. Formation of the 7-membered ring-fused tricyclic indole
skeleton was accomplished using a palladium-catalyzed Heck insertion–allylic
amination cascade. Vicinal difunctionalization of the 7-membered ring
was realized via a rhodium-catalyzed aminoacetoxylation.